Lexicon development via shared translation database

ABSTRACT

A speech translation system and methods for cross-lingual communication that enable users to improve and customize content and usage of the system and easily. The methods include, in response to receiving an utterance including a first term associated with a field, translating the utterance into a second language. In response to receiving an indication to add the first term associated with the field to a first recognition lexicon, adding the first term associated with the field and the determined translation to a first machine translation module and to a shared database for a community associated with the field of the first term associated with the field, wherein the first term associated with the field added to the shared database is accessible by the community.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 13/008,346, filed on Jan. 18, 2011, allowed, which is a continuationin part of co-pending U.S. patent application Ser. No. 12/689,042 filedon Jan. 18, 2010; which is a continuation in part of U.S. patentapplication Ser. No. 12/424,311 filed on Apr. 15, 2009, now U.S. Pat.No. 8,204,739, issued Jun. 19, 2012, which claims the benefit of U.S.Provisional Patent Application No. 61/045,079 filed on Apr. 15, 2008,U.S. Provisional Patent Application No. 61/092,581 filed on Aug. 28,2008, and U.S. Provisional Patent Application No. 61/093,898 filed onSep. 3, 2008, the contents of which are incorporated herein by referencein their entirety.

BACKGROUND

Field of the Invention

The present invention is directed generally to speech-to-speechtranslation systems for cross-lingual communication and, moreparticularly, to a method and system for field maintenance that enablesusers to add new vocabulary items and to improve and modify the contentand usage of their system in the field, without requiring linguistic ortechnical knowledge or expertise. In various examples, the systems andmethods disclosed also enable non-expert users to improve and modify thecoverage and usage of their system in the field and to maximize theusefulness for effective communication without requiring linguistic ortechnical knowledge or expertise and provide a novel.

Description of the Invention Background

Automatic speech recognition (ASR) and machine translation (MT)technologies have matured to the point where it has become feasible todevelop practical speech translation systems on laptops or mobiledevices for limited and unlimited domains. Domain limitedspeech-to-speech systems, in particular, have been developed in theresearch field and in research laboratories for a variety of applicationdomains, including tourism, medical deployment and for militaryapplications. Such systems have been seen before in the works of A.Waibel, C. Fugen, “Spoken language translation” in Signal ProcessingMagazine, IEEE May 2008; 25(3):70-79; and Nguyen Bach, Matthias Eck,Paisarn Charoenpornsawat, Thilo Köhler, Sebastian Stoker, ThuyLinhNguyen, Roger Hsiao, Alex Waibel, Stephan Vogel, Tanja Schultz and AlanW. Black, for examples. “The CMU TransTac 2007 eyes-free and hands-freetwo-way speech-to-speech translation system,” In Proc. of the IWSLT,Trento, Italy, October 2007. They are limited, however, in that theyoperate with a limited vocabulary which is defined by the developers ofthe system in advance, and is determined by the application domain, andthe location where it is envisioned the system will be used. Thusvocabularies and language usage are determined largely based on examplescenarios and by data that is collected or presumed in such scenarios.

In field situations, however, actual words and language usage deviatefrom the anticipated scenario of the laboratory. Even in simple domainssuch as tourism language usage will vary dramatically in the field as auser travels to different locations, interacts with different people andpursues different goals and needs. Thus, new words and new expressionswill always arise. Such new words—in speech recognition parlance“out-of-vocabulary” (OOV) words will be misrecognized as anin-vocabulary word and then translated incorrectly. The user may attempta paraphrase, but if a critical word or concept (such as a person or acity name) cannot be entered or communicated, the absence of the word orexpression may lead to communication break-down.

Despite the need for user modifiable speech-to-speech translationsystems, an actual solution has so far not been proposed. While adding aword to the system may seem to be easy, making such modifications provesto be extraordinarily difficult. Appropriate modifications must be madeto many component modules throughout the entire system, and most moduleswould have to be retrained to restore the balance and integratedfunctioning of the components. Indeed, about 20 different modules wouldhave to be modified or re-optimized to learn a new word. Suchmodifications require expertise and experience with the components of aspeech translation system, and as a result, to the inventor'sunderstanding, such modifications have so far been done only in thelaboratory by experts, requiring human expertise, time and cost.

For example, if a system designed for users in Europe does not containthe name “Hong Kong” in the vocabulary. Once a speaker speaks thesentence “Let's go to Hong Kong”, the system will recognize the closestsounding similar word in the dictionary and produce: “Let's go to homecall”. At this point it is not obvious if the error was the result of arecognition error or result of the absence of this word in the entirespeech-to-speech translation system. The user therefore proceeds tocorrect the system. This can be done by one of several correctiontechniques. The simplest might be re-speaking or typing, but it canalternatively be done more effectively by cross-modal error correctiontechniques as described by other disclosures and prior art (Waibel, etal., U.S. Pat. No. 5,855,000). Once the correct spelling of the desiredword sequence has been established (“Let's go to Hong Kong”), the systemperforms a translation. If “Hong Kong” is in the dictionary, the systemwould proceed from there normally, performing translation and synthesis.If, however, it is absent from the recognition and translationdictionary, the system would need to establish if this word is a namedentity or not. Finally, and most importantly, even if a name or word canbe translated properly to the output languages by user intervention,without learning it, the system would fail again when the user speaksthe same word the next time around.

Unfortunately, learning a new word cannot be addressed just by simplytyping in a new word in a word list, but it requires changes at about 20different points and at all levels of a speech translation system.Presently it also involves manual tagging and editing of entries,collection of extensive databases involving the required word,retraining of language model and translation model probabilities andre-optimization of the entire system, so as to re-establish theconsistency between all the components and components' dictionaries andto restore the statistical balance between the words, phrases andconcepts in the system (probabilities have to add up to 1, and thus allwords would be affected by a single word addition).

As a result, even small modifications of existing speech translationsystems have generally required use of advanced computing tools andlinguistic resources found in research labs. For actual field use,however, it is unacceptable to require every modification to be done atthe lab, since it takes too much time, effort and cost. Instead, alearning and customization module is needed that hides all thecomplexity from the user, and performs all the critical operations andlanguage processing steps semi-autonomously or autonomously behind thescenes, and interacts with the human user in the least disruptive mannerpossible by way of a simple intuitive interface, thereby eliminating theneed for linguistic or technical expertise in the field altogether. Inthe present invention, we provide a detailed description for a learningand customization module that satisfies these needs.

Speech translation systems have achieved a level of performance that nowmakes effective speech translation in broad popular use a reality, andpermits its use on small portable platforms such as laptop computers,PDA's and mobile telephones. As such, it is impractical to send speechtranslation systems back to the developer every time errors occur,vocabulary items are missing. Similarly, field situations dictate, thata user must be able to deal with errors quickly and effectively, andthat effective communication is supported through the device, however,imperfect its performance. Error handling becomes a critical part ofdelivering fast and effective speech communication. Errors areproblematic only, if they cannot be aborted quickly, corrected quicklyand system performance improve (learn) from the correction. Thus, thereis a need for systems and methods that use machine translationtechniques to provide techniques to efficiently deal with errors duringtranslation. There are also needs to provide users of such systems andmethods with more robust capabilities to facilitate translation andenable the user to take advantage of its customized system such asthrough the creation of one or more added modules including favoriteslists, language learning tools and notification of third partyinformation based upon usage of the system and methods.

SUMMARY OF THE INVENTION

In various embodiments, the present invention solves the foregoingproblems by providing a system and methods for updating the vocabularyof a speech translation system. A computer assisted method is providedfor overriding the recognition or translation of an utterance input in aspeech translation system for translating a first language into a secondlanguage. The methods include, in response to receiving an utteranceincluding a first term associated with a field, translating theutterance into a second language. In response to receiving an indicationto add the first term associated with the field to a first recognitionlexicon, adding the first term associated with the field and thedetermined translation to a first machine translation module and to ashared database for a community associated with the field of the firstterm associated with the field, wherein the first term associated with afield added to the shared database is accessible by the community.

Those and other details, objects and advantages of the present inventionwill become better understood or apparent from the following descriptionand drawings showing embodiments thereof.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings illustrate examples of embodiments of thepresent invention. In such drawings:

FIG. 1 is a block diagram illustrating a speech-to-speech translationsystem constructed according to an embodiment of the present invention;

FIG. 2 illustrates an example of a graphical user interface that isdisplayed to user via a tablet interface;

FIG. 3 is a flow chart illustrating the steps of speech-to-speechtranslation performed according to an embodiment of the presentinvention in FIG. 1;

FIG. 4 is a flow chart illustrating the steps by which the system learnsfrom corrections made by the user (Correction and Repair Module);

FIG. 5 is a flow chart illustrating the steps by which users can add newwords to system (User Field Customization Module);

FIG. 6 is a flow chart illustrating one example of methods by which thesystem automatically generates the translation and pronunciations fornew words the user wishes to add to the system;

FIG. 7 is a flow chart illustrating one example of a method to verifynew word input via a multimodal interface;

FIG. 8 illustrates an example of a visual interface to displayautomatically generated word information;

FIG. 9 is a flow chart illustrating the steps required to trainclass-based MT models;

FIG. 10 is a flow chart illustrating the steps of applying class-basedMT to an input sentence; and

FIG. 11 is a diagram illustrating possible features used duringword-class tagging via statistical or machine learning approaches.

FIG. 12 is a flow chart illustrating the steps required to add an outputsentence-pair from the speech translation system to a translationfavorites list.

FIG. 13 is a flow chart illustrating the steps required to playback,edit, add or delete a sentence-pair in the translations translationfavorites list.

FIG. 14 illustrates an example of the steps required to add an outputsentence from the speech translation system to an active languagelearning drill.

FIG. 15 illustrates an example of the steps required in a languagelearning module to present language learning drills to a user.

FIG. 16 illustrates an example of the steps required in an informationextraction module to present targeted advertisements or supportiveinformation to a user.

FIG. 17 illustrates an example of a graphical user interface for a“translation favorites” list.

FIG. 18 illustrates an example of a graphical user interface for addingphrases generated by the speech translation system to a user's“translation favorites” list.

DETAILED DESCRIPTION

Various embodiments of the present invention describe methods andsystems for speech-to-speech translation. Embodiments may be used toadapt to the user's voice and speaking style via model adaptation. Infurther embodiments, the user can correct recognition errors and thesystem can explicitly learn from errors that the user corrected, therebymaking it less likely that these errors occur again in the future. Thepresent invention enables the user to customize the vocabulary to his orher individual needs and environment by either adding new words to thesystem, or selecting predefined dictionaries that are optimized for aspecific location or task. When adding new words a multimodal interfaceallows the user to correct and verify automatically generatedtranslations and pronunciations. This allows the user to add new wordsto the system when the user has no knowledge of the other language. Inan embodiment, the system is further configured to transmit any newvocabulary inputted by a user to a community of users. This data iscollated and dictionaries are automatically generated which can then bedownloaded by any user.

FIG. 1 illustrates a block diagram overview of an example of a fieldmaintainable speech-to-speech translation system according to thepresent invention. In this example the system operates between twolanguages L_(a) and L_(b). This is the typical implementation of aspeech-to-speech dialog system involving speech-to-speech translation inboth directions, from L_(a) and L_(b) and from L_(b) and L_(a). However,the bi-directionality of this configuration is not a prerequisite forthe present disclosure. A uni-directional system from L_(a) and L_(b),or a multi-directional system involving several languages L₁ and L_(n)could equally benefit from the present invention. The system has two ASRmodules 2 and 9, that recognize speech for L_(a) and L_(b),respectively, and produce text corresponding to L_(a) and L_(b),respectively using acoustic model 18, ASR class-based language model 19and a recognition lexicon model 20 (shown in FIG. 3), and are means forreceiving and recognizing such utterances. In this example, we used the“Ninja” speech recognizer system developed at Mobile Technologies, LLC.Other types of ASR modules which may be used include speech recognizersdeveloped by IBM Corporation, SRI, BBN or at Cambridge or Aachen.

The system also includes two machine translation modules 3 and 8, whichtranslate text from L_(a) and L_(b) and from L_(b) and L_(a),respectively (module 11). The MT module used in this example was the“PanDoRA” system developed at Mobile Technologies, LLC. Other MT modulescould be used such as those developed by IBM Corporation, SRI, BBN or atAachen University.

Two text-to-speech engines, 4 and 7 each corresponding to one of themachine translation modules 3 and 8, are configured to receive textproduced from a corresponding ASR unit. The output text is transferredto the respective MT module, 3 or 8, that translate text from L_(a) andL_(b) and from L_(b) to L_(a), respectively. The TTS module generatesaudio output to convert at least one text word in L_(a) to speech via anoutput device 5, such as a loud speaker, and at least one text word inL_(b) to speech via device 5 or another output device, such as a loudspeaker 6, respectively. For this example a Cepstral US module was used.Any TTS modules which support Windows SAPI (speech applicationprogramming interface) conventions could also be employed.

A correction and repair module 11 allows the user to correct the systemoutput via multiple modalities; including speech, gesture, writing,tactile, touch-sensitive and keyboard interfaces, and enables the systemto learn from the user's corrections. The correction and repair modulemay be of the type such as that disclosed in U.S. Pat. No. 5,855,000. Auser field customization module 12, provides an interface for users toadd new vocabulary to the system, and can also select an appropriatesystem vocabulary for their current situation. For example, triggered bya change in location, as determined by the GPS coordinates indicatingthe current location of the device, or an explicit selection of task orlocation by the user.

The user can access the user field customization module 12 and interactwith the system via a graphical user interface displayed on the screen(or active touch screen) of the device 13, and a pointing device 14,including a mouse or pen. An example of a graphical user interface isshown in FIG. 2. In this example, the device 13 displays the text ofaudio input of a L_(a) and corresponding text in window 15. Machinetranslation of text L_(a) in the second language L_(b) is displayed inwindow 16.

In an embodiment, the same microphone and loud-speaker can be used forboth languages. Thus, microphones 1 and 10 can be a single physicaldevice, and speakers 5 and 6 can be a single physical device.

In an embodiment, an information extraction module, 12 a, will bepresent which extracts information from recent system logs 14 e (forlanguage La) and 14 f (for language Lb), and presents targetedadvertisement and supportive information via a graphical user interfacedisplayed on the screen of the device 13. Relevant information will beobtained from the internet or a local knowledgebase.

In an embodiment, a language learning module, 12 b, will be presentwhich extracts information from recent system logs (14 e and 14 l) tosubsequently be used for language learning. Drills are automaticallygenerated based on recent system usage by the user, additionally theuser can choose any sentence output from the system to add to his/heractive learning drill (step 34 c).

A flow chart illustrating the operation of an example of the method ofthe present invention is shown in FIG. 3. First, the speech recognitionsystem is activated by the user at step 15 b. For instance, a button canbe selected on the graphical user interface (FIG. 2, item 15 b) or on anexternal physical button (not shown). The user's speech (item 25) isthen recognized by one of the ASR modules in step 27; module 2, if theuser is speaking L_(a), and module 9 if the user is speaking L_(b). TheASR modules 2 and 9 apply three models: acoustic model 18, ASRclass-based language model 19 and a recognition lexicon model 20. Thesemodels are language specific and each ASR module contains its own set ofmodels. The resulting text of the user's speech is displayed via the GUIon the device screen 13 at step 28.

Translation is then applied via MT module 3 or 8 based on the inputlanguage (step 29). MT modules 3 and 8, apply three main models: atagging or parsing [Collins02] model to identify word classes (model22), a class-based translation model (model 23), and a class-basedlanguage model (model 24). The tagging model 22 may be any suitable typeof tagging or parsing model such as the types described in J. Lafferty,A. McCallum, and F. Pereira, “Conditional random fields: Probabilisticmodels for segmenting and labeling sequence data,” In Proceedings of18th International Conference on Machine Learning, pages 282-289, 2001(“Lafferty01”) or Michael Collins, “Parameter estimation for statisticalparsing models: Theory and practice of distribution-free methods” (2004)In Harry Bunt, John Carroll, and Giorgio Satta, editors, NewDevelopments in Parsing Technology, Kluwer. Other models that areapplied during the machine translation include distortion models, whichconstrain how words are re-ordered during translation, and sentencelength models. A detailed description of class-based machine translationis given below. The resulting translation is displayed via the GUI ondevice 13 as shown in step 30.

To help the user determine if the translation output is adequate, theautomatically generated translation (FIG. 2, item 16) is translated backinto the input language via MT module 3 or 8 and displayed withparentheses under the original input as illustrated for example in FIG.2, item 15 a. If the confidence of both speech recognition andtranslation are high (step 31) as determined by the ASR model, 2 or 9,and the MT module, 3 or 8, spoken output (item 26) is generated via loudspeakers 5 or 6, via TTS modules 4 or 7 (step 33). Otherwise, the systemindicates that the translation may be wrong via the GUI, audio and/ortactical feedback. The specific TTS module used in step 33 is selectedbased on the output language.

Thereafter, if the user is dissatisfied with the generated translation,the user may intervene during the speech-to-speech translation processin any of steps from 27 to 33 or after process has completed. Thisinvokes the Correction and Repair Module 11 at (step 35). The Correctionand Repair Module (Module 11) records and logs any corrections the usermay make, which can be later used to update ASR modules 2 and 9 and MTmodules 3 and 8 as described in detail further below in this document.If the correction contains a new vocabulary item (step 36), or if theuser enters the field customization mode to explicitly add a new word tothe system in step 15 c, or if a new word is automatically detected inthe input audio using confidence measures or new word models, such asthe method described in Thomas Schaaf, “Detection of OOV words usinggeneralized word models and a semantic class language model,” in Proc.of Eurospeech, 2001 in step 15 d; the User Field Customization Module(Module 12) is invoked.

In addition to the consecutive translation mode where the user holdsdown a push-to-talk button (step 15 b) and speaks only a singleutterance per-term, in an embodiment of the system a simultaneoustranslation mode will be present. In this mode no button push isrequired but the system continuously recognizes and translates allspeech present on both microphone inputs (FIG. 1, items 1 and 10).Continuously recognition and simultaneous translation is shown by steps15 e and 34 a.

In addition to the speech translation modes the user can exit the mainsystem to enter either the “field customization” mode (step 15 c), the“translations favorites” mode (step 15 f), or the “language learning”mode (step 15 g).

During use any sentence-pair outputted by the system can be added to theusers “translations favorites” list (step 34 b).

The User Field Customization Module (Module 12) provides a multimodalinterface to enable users to add new words to the active systemvocabulary. When a new word or phrase is added by a user the ASR, MT andTTS models (items 17, 21 and 33 a) are updated as required.

A common set of classes (for example person names, place names, andorganization names) is used in both ASR and MT for both languages. Thisprovides a system-wide set of semantic slots that allows new words to beadded to the system. The names, special terms and expressions that occurwithin these classes are the words that are most variable depending ondifferent users' deployments, locations, cultures, customs and tasks,and thus they are in greatest need of user-customization.

In a preferred example, the specific classes used are dependent on theapplication domain of the system. The classes may include semanticclasses for named-entities; person, place and organization names; ortask-specific noun phrases; for example: names of foods, illnesses ormedicines; and another open class for words or phrases that don't fitinto any of the predefined classes. Syntactic classes or wordequivalence classes such as synonyms could also be used. Examples ofapplication domains include, but are not limited to, tourist, medical,peace keeping, and the like. In an example, classes required in thetourist application domain include names of persons, cities, foods andthe like. In another example, for a medical professional applicationclasses required include names of diseases, medications, anatomicalnames, and the like. In another example, classes required for apeace-keeping application include names of weapons, vehicles, and thelike. To enable field customizable speech translation, the systempermits error correction and later learning from these errors throughthe operation of the correction and repair module 11 in combination witha user field customization module 12.

Correction and Repair Module

The Correction and Repair Module (module 11) enables a user to intervenein the speech-to-speech translation process at any time. The user mayeither identify and log an error, or, if he/she wishes, correct an errorin the speech recognition or translation output. Such user interventionis of considerable value, as it provides immediate correction in thehuman-human communication process, and opportunities for the system toadjust to user needs and interests and to learn from mistakes. A flowdiagram illustrating this error feedback functionality is shown in FIG.4. If the user is dissatisfied with a translation of an utterance (i.e.an error occurs) the user can log the current input (step 40). Thesystem will save audio of the current utterance as well as otherinformation to a log file. This can be accessed and corrected by theuser at a later time, or can be uploaded to a community database toallow expert users to identify and correct errors.

The user can also correct the speech recognition or machine translationoutput via a number of modalities. The user can correct the entireutterance, by re-speaking it or entering the sentence via a keyboard orhandwriting interface. Alternatively a user can highlight an erroneoussegment in the output hypothesis via the touch-screen, mouse or cursorkeys and correct only that phrase or word, using the keyboard,handwriting, speech, or explicitly spelling out the wordletter-for-letter. The user can also select an erroneous segment in theoutput hypothesis via the touch screen and correct it by selecting acompeting hypothesis in an automatically generated drop-down list, or byreentering it by speech, or by any other complementary modality (e.g.,handwriting, spelling, paraphrasing, etc.). These methods and how tosuitably combine complementary repair actions build on methods proposedby Waibel, et al., in U.S. Pat. No. 5,855,000 for multimodal speechrecognition correction and repair. Here they are applied to the speechrecognition and translation modules of interactive speech translationsystems.

If the user corrects the speech recognition output (step 43) the systemfirst determines if the correction contains a new word (step 44). Thisdetermination is made by checking for the word in the recognitionlexicon model 20 associated with each language, L_(a) and L_(b). If theword is not found the system prompts the user to add the new word to theactive system vocabulary if desired (FIG. 5, step 50). Otherwise, theprobabilities in the ASR models (FIG. 3, item 17) are updated to reducethe likelihood of the same error occurring again. This can be performedin a discriminative manner where probabilities of the corrected wordsequence are increased, and those of close-competing hypotheses arereduced.

A user can also correct the machine translation output if they havesufficient language expertise. The same modalities as used in the ASRcase can be used. If the machine translation output is corrected by theuser (step 45) and the correction contains a new word, then the user isprompted with a dialog enabling them to add the new word to the activesystem vocabulary (FIG. 5, step 50). If the correction only containswords which are already in the active system vocabulary, then themachine translation models (FIG. 3, item 21) are updated. Specifically,an implementation can be used, where phrases are extracted from thecorrected sentence pair and these are folded into translation models.The target language model used can be updated in a similar way to theASR case.

In the present invention, we introduce an abort action into thecorrection module. The abort action instantaneously aborts thespeech-translation processes. It removes any hypotheses or partialhypotheses that may have already been output and resets the system toaccept a new input. The abort action can be initiated by the user eitherdepressing the push-to-talk button via the graphical user interfaceagain (thus reinitiating recording for more input without waiting beforethe old one completes processing) or by shaking the phone to stop allprocessing. Output from internal accelerometers [14 a] embedded in thehardware device or from an embedded camera [14 b] that measures rapidshaking movement are used to determine if the device is being shaken bythe user. The determination of the wrist shake by the user is then usedto abort all processing that may be in progress and clear's the device'sscreen. The abort action can also be confirmed acoustically to the userwith a crumbling paper noise, or other sound icon that confirmsacoustically during field use that the speech translation process hasbeen aborted. The simplicity of a shake of a wrist as well as theaccompanying methods to confirm the abort by way of an acoustic soundicon, noise, beep, keyword or signal, provides simple fast, effective,unambiguous and intuitive signaling for both dialog partners thatcorrection has taken place.

User Field Customization Module

User field customization module 12 enables the system to learn new wordsin cooperation with the user. Prior systems do not allow users to modifyvocabularies in speech-to-speech translation systems. Unlike priorsystems, user field customization model 12 enables the user to makeincremental modifications in a running system that are relatively easyto perform for a non-expert, with minimal or no knowledge of computerspeech and language processing technology or of linguistics. Model 12offers such field customization by providing and accepting certaineasy-to-understand feedback from the user, and based on this feedbackderiving all the necessary parameters and system configurationsautonomously. Field customization module 12 accomplishes thisthrough: 1) an intuitive interface for user-customization, and 2)internal tools that automatically estimate all the internal parametersand settings needed for user customization, thereby relieving the userfrom this burden.

For unidirectional translation, the system processes a minimum of fourpieces of information about the word or phrase to add a new word orphrase to the active system vocabulary. These include:

-   -   class (i.e. semantic or syntactic class of the new entry)    -   word in language L_(a) (i.e. written form in L_(a))    -   pronunciation of word in L_(a)    -   translation of word in L_(b) (i.e. written form in L_(b))        For a bidirectional translation, the system also requires input        of the pronunciation of the new word in L_(b). The L_(b) enables        the TTS to generate audio output and the ASR module for L_(b) to        recognize the new word.

A flow chart illustrating the steps of operation of the user fieldcustomization model 12 is shown, for example, in FIG. 5. When a new wordis encountered by the system, based on a corrective intervention via thecorrection and repair model 11 in the previous section, it will promptthe user (FIG. 5, step 50) to determine if this word should be“learned”, i.e., added to the active system vocabulary. If so, a wordlearning mode is activated and the field customization module 12 beginsto act. Note that field customization or new-word learning need not onlyresult from error correction dialogs. The user may also specificallychoose to enter a word learning mode from a pull-down menu, to add a newword or a list of new words a priori. New word learning, could also betriggered by external events that cause a sudden need for differentwords, such as specialty terms, names, locations, etc. In all suchinstances, however, the system must collect the above information.

After the user indicates that he/she wishes to add a new word to thesystem vocabulary (step 50), the system first compares the word toentries in a large background recognition lexicon (item 50 d), as listedin FIG. 5, step 50 a. If the word is present in this lexicon then thelisted pronunciations and matched n-gram entries from a large backgroundspeech recognition language model (item 50 e) are included into theactive ASR models (item 17). This step is shown in FIG. 5, step 50 b. Ifthe word is not present in the background recognition lexicon (item 50d) the system next compares the word to a large external dictionary,which is either contained locally on the device, or is a dictionaryservice that can be accessed via the Internet, or is a combination ofboth. The external dictionary consists of entries of word translationpairs. Each entry contains pronunciation and word-class informationwhich enables the new word to be easily added to the active systemvocabulary. Each entry also contains a description of each word-pair inboth languages. This will allow the user to select the appropriatetranslation of the word, even if they have no knowledge of the targetlanguage. If the new word is contained within the external dictionary(step 51), the system displays a list of alternative translations of theword with a description of each (step 52). If the user selects one ofthe predefined translations from the dictionary (step 53), then they canverify the pronunciation and other information provided by thedictionary (step 53 a), and the edit this if necessary. The phoneticpronunciation can be corrected using any suitable notation, including;IPA pronunciation, a local method of pronunciation notation, includingKatakana for Japanese or Pingying for Chinese, a pseudo-phoneticspelling for English, or any other suitable phonetic notation. Since auser may not know how to write the correct phonetic spelling for a word,alternative pseudo-phonetic transcription are used in combination withsynthesis to sound out the new word aloud. In this way, the user maytype a name or new word according to his/her orthographic conventions,while the internal letter to sound conversion routines provide theconversion into phonetic notation based on each spelling. The word canthen be played back according to the phonetic string, and if notsatisfactory the user can iterate. Finally, when a satisfactory readingis achieved, the new word is then added to the active system vocabulary.

To add a new word to the active system vocabulary, three steps arerequired (steps 59, 59 a, 59 b). First the word and its translation areadded to the ASR recognition lexicons of modules 2 and 9 (step 59). Theword is added to this recognition lexicon 20 along with thepronunciation(s) given by the dictionary. As the user has just enteredthis word its probability of occurrence is set to be greater thancompeting members of the same class within the ASR class-based languagemodel 19. This is to make words that were specifically added by the usermore likely. Next, the word and its translation are added to the MTmodels (FIG. 3, item 21), enabling the system to translate the new-wordin both translation directions. Finally, the word is registered with theTTS pronunciation model (FIG. 3, model 33 a), which enables the systemto pronounce the word correctly in both languages.

When the new word entered by the user is not found in the externaldictionary, the system will automatically generate the informationrequired to register the word into the active system vocabulary, andwill verify this information with the user. First, the class of the newword is estimated via a tagging model (FIG. 3, model 22) using thesurrounding word context if it is available (step 54). Next, thepronunciation and translation of the new word are automaticallygenerated via either rule-based or statistical models (step 55). Theresulting information is then shown to the user via a multimodalinterface (step 58). The system prompts the user to verify (step 58) orcorrect (step 57) the automatically generated translation orpronunciation. Finally, after the user has verified this information,the new word is added to the active system vocabulary (steps 59, 59 a,59 b). To dynamically add a new word (specifically,“word+pronunciation+word class”) to the ASR vocabularies (59), therecognition lexicon 20 (which is typically stored as a tree-structure,within ASR Modules 2 or 9) is searched and then updated to include thenew word. This enables the new word to be added to the recognitionvocabulary dynamically, and it can thus be recognized, immediately, ifspoken in the following utterance. The ASR system does not need to bere-initialized or re-started as in prior systems.

Similarly, a new word (specifically, “word+translation+word class”) canbe appended to the MT translation model (59 a), the translation model 23(which is can be stored as a hash-map within MT modules 3 and/or 8) issearched and an new translation-pair containing the new word itstranslation, and word class is appended. This enables the new word to beadded to the MT modules 3 and/or 8, dynamically, and the new word willbe translated correctly in proceeding utterances. The MT systems do notneed to be re-initialized or re-started as in prior works.

Estimating all this information automatically is essential, so that anon-expert user in the field can perform the task of customization. Inthe following, we describe in detail, how this critical informationabout a word is estimated automatically, and then, how it can beobtained or verified intuitively from the user.

Generation of Pronunciations and Translations of New Words As users ofspeech-to-speech translation systems usually have limited or noknowledge of phonetics, linguistics, language technology, and often evenhave no knowledge of the word and its use in the other language, theycannot be expected to provide a translation and all the pertinentinformation (pronunciation, orthography, word use, etc.) of eachnew-word they wish to add to the system. Thus, when the user enters anew-word, the system estimates the word-class and generates thetranslation and pronunciation information of the word in both languages,automatically.

To register a new word into the active system vocabulary, thetranslation of the word and pronunciations for both the word and itstranslation are required. Generating this information can be implementedas a three-step process as shown, for example, in FIG. 6. First, thepronunciation of the word is generated (step 60). Based on the charactersequence of the word and its pronunciation, a translation is generated(step 61). Next, the pronunciation of the new word in the targetlanguage is generated (step 62) using information generated in previoussteps. Two examples for generating this information using differenttechniques within a Japanese-English Field Maintainable S2S TranslationSystem are shown on the left hand side of FIG. 6. To add a new Englishword “Wheeling” (item 61) to the system, first the English pronunciationis generated via machine learning (step 65). Machine learning may beconducted by any suitable technique such as those described by Damper,R. I. (Ed.), Data-Driven Techniques in Speech Synthesis. Dordrecht, TheNetherlands: Kluwer Academic Publishers (2001). Next, thetransliteration of this word in Japanese is automatically generated viastatistical machine transliteration (step 66), and the Japanesepronunciation is then generated via manually defined rules (step 67).Transliteration may be accomplished by using any suitable statisticalmachine transliteration engine. Examples include those discussed by K.Knight and J. Graehl, Machine transliteration. Computational Linguistics24 4 (1998), pp. 599-612; and Bing Zhao, Nguyen Bach, Ian Lane, andStephan Vogel, “A Log-linear Block Transliteration Model based onBi-Stream HMMs”, to appear in HLT/NAACL-2007. The resulting information(item 68) is then verified by the user by way of acoustic playback andby the phonetic string, before registering the word into the activesystem vocabulary.

Similarly, to add a new Japanese word “Wakayama” (item 70) to thesystem, first the Japanese pronunciation is generated via manuallydefined rules (step 71). Next, the transliteration of this word inJapanese is automatically generated via rule-based transliteration (step72), the English pronunciation is then generated via manually definedrules (step 73). The rule based transliteration may be performed usingmethods of Mansur Arbabi, Scott M. Fischthal, Vincent C. Cheng, andElizabeth Bar, “Algorithms for Arabic name transliteration,” IBM Journalof research and Development, 38(2):183

193, 1994. The resulting information (item 74) is then verified by theuser before registering the word into the active system vocabulary.

The user can verify the generated translation and pronunciation viaaudible output. Alternatively written form may be used if consideredmore suitable for the user, given their native language (i.e. in “HanyuPinyin” for Chinese, or “Romaji” for Japanese if the user is an Englishspeaker). The user may edit the translation and/or pronunciation ifrequired. Once approved by the user, the word and word characteristicsare added to the multilingual system dictionary.

The system also eliminates the need for a translation of each new wordthat is added to the dictionary by automatically generating the requiredinformation with the assistance of interactive user input. An example ofa user interface is shown in FIG. 3.

Interactive User Interface

Thereafter, the system consults the user to confirm and verify theestimated linguistic information. This is done in an intuitive manner,so as not to presume any special linguistic or technical knowledge.Thus, a suitable interface is used. In the following we describe theuser interaction during new word learning.

In the interface, the user may select a “new-word” mode from the menu,or the new word learning mode could be invoked after a user correctionhas yielded a new/unknown word. In the window pane that appears he/shecan now type the desired new word, name, special term, concept,expression. Based on the orthographic input in the user's language (thiscan be character sets different from English, e.g., Chinese, 64 CIP/CIPJapanese, Russian, etc.). The system then generates a transliteration inRoman alphabet and the words predicted pronunciation. This is done byconversion rules that are either hand written or extracted frompreexisting phonetic dictionaries or learned from transliterated speechdata. The user then views the automatic conversion and can play thesound of the generated pronunciation via US. The user may iterate andmodify either of these representations (script, Romanizedtransliteration, phonetic transcription, and its sound in eitherlanguage) and the other corresponding entries will be regeneratedsimilarly (thus a modified transcription in one language may modify thetranscription in the other).

The system further automatically selects the most likely word class thatthe new word belongs to based on co-occurrence statistics of other words(with known class) in similar sentence contexts. The new word windowpane also allows for a manual selection (and/or correction) of thisclass identity, however, so that the user can override any suchestimated class assessment.

In summary, given a new word/phrase from user, the system will

-   -   Automatically classify semantic class of entry (used by ASR and        MT components)    -   Automatically generate pronunciation for word (used by ASR and        TTS for L1)    -   Automatically generate translation of word (used by both MT        components)    -   Automatically generate pronunciation of translation (used by ASR        and TTS for L2    -   Allow user to correct/edit automatically generated data as        required    -   Provide other modalities for user to verify if automatically        generated translation is adequate. (i.e. listen to the        pronunciation of the word via TTS)

If the user enters a word that does not match any of the pre-definedclasses within the system, the user can assign it to the ‘unknown’class. For ASR, the ‘unknown’ class is defined by words that occurred inthe training data but not in the recognition lexicon. For SMT bilingualentries that do not occur in the translation lexicon are set to theunknown tag in the target language model.

Intra-Class Probability and Relevance Boosting

Neither of these input methods requires linguistic training and providesan intuitive way for the user to judge if a new word was suitablyrepresented. The user may then accept this new word entry by adding theword to a “multilingual system-dictionary”, that is a user's individuallexicon. The overall system merges standardized lexica with customizedlexica into the user's runtime dictionary.

In addition to the above five entries, an intra-class probability P(w|C)is also defined. In this fashion it is possible for the system todifferentiate between words belonging to the same class. Thus words thatare closer to the user's tasks, preferences and habits will be preferredand a higher intra-class probability assigned. This boosting of higherintra-class probability is determined based on relevance to the user,where relevance is assessed by observing:

The new word entry and its regency.

-   -   New words entered are naturally more likely to be used in the        immediate future, since the user indicated that he/she wanted        them by entering them, and thus intra-class probabilities are        boosted (increased) over alternate existing class entries

Correlation between the new word and user activities, interests andtasks, including

-   -   Distance for locations such as city names, landmarks, places of        interest, etc.    -   History of past use    -   Co-occurrence statistics (Sushi correlates better with Tokyo        than with Bogota)

General saliency of the new word, including

-   -   Population of cities    -   Recent mention in the Media

Such observations and relevance statistics are collected based on theuser's observed location, history or activity, and/or alternatively byobserving the occurrence of the system's new word in a large backgroundlanguage resource such as the internet. Such statistics may be collectedmonolingually, in a data-rich language and applied to the translationdictionary and translation language model.

The relevance of boosted words may also decay over time, as the user'snew activities and tasks render such words less likely over time and/orif new information (as the arrival at a different city) make a subclassof words less relevant.

Cross-Modal Entry

Optionally, a new word is entered by one of the following:

-   -   Speaking: User speaks the new word. All information such as        pronunciations and transliteration is estimated by new word        models, translation models, background dictionaries as before        but based on the acoustic input. The system may engage in a        verbal dialog to select the class identity and other pertaining        information.    -   Spelling: User spells new word acoustically. This input method        generally improves the likelihood of a correct transliteration        over speaking it. It may also be used complementarily to        speaking and other input modalities,    -   Handwriting: User enters new word by handwriting. This input        method generally improves the likelihood of a correct        transliteration over speaking it. It may also be used        complementarily to speaking, spelling, or other input        modalities,    -   Browsing: New words may also be selected by interactive        browsing. Here the system may propose related, relevant new        words by searching the internet for texts with similar        statistical profiles as the user's recent usage history and/or        recent selected entered new words.        Remote New Word Learning and Shared Lexicon Development Over the        Internet

The methods described in the previous sections are all aimed at allowingan individual user to customize a speech translation system to his/herindividual needs and tasks in the field. Many of such usercustomizations could, however, be useful to other users as well. In anembodiment, user customizations are uploaded to a community widedatabase, where names, special terms, or expressions are shared betweeninterested parties. The vocabulary entries, translations and class tagsare collected and related to similarly interested communities.Subsequent users can download these shared community resources and addas resource to their own system.

Alternatively, users may choose to only upload poorly translatedsentences, to request manual translation from the community. For suchincorrect or incomplete source words or sentences and their missing orincorrect translations other human users can provide online correctionand translation on a volunteer (or paid fee) basis. The resultingcorrections and translations are once again resubmitted into the updatedshared community translation database.

Unsupervised Adaptation

After correction, repair and new word learning, finally, we obtain acorrected hypothesis, and thus a true transcript or translation of aspoken sentence. The speech-to-speech translation device or systemautomatically can use the fact that such ground truth has been providedto further adapt the ASR modules (FIG. 1, module 2 or 9) to the primaryuser of the device. Such adaptation is designed to improve the accuracyand usability of the device. Two specific methods of adaptation areperformed. First, adaptation of the system to better recognize theuser's voice; acoustic model and pronunciation model adaptation, andsecond, adapting to the user's style of speech by way of language modeladaptation. Profiles are used to store adaptation data for specificusers and can be switched in the field.

Class-Based Machine Translation

In the previous sections, we have described error repair and new wordlearning. In these modules, reference was made to class-based machinetranslation. In the following, we describe the detailed functioning ofsuch class-based machine translation.

The Approach

State of the art machine translation systems perform translation on theword-level. This is evident from prior translation systems includingthose described in the following three documents; (1) P. Koehn, H.Hoang, A. Birch, C. Callison-Burch, M. Federico, N. Bertoldi, B. Cowan,W. Shen, C. Moran, R. Zens, C. Dyer, O. Bojar, A. Constantin, and E.Herbst, ‘Moses: Open source toolkit for statistical machinetranslation’, In Proc. ACL, 2007 (“[Koehn07”); (2) D. Chiang, A. Lopez,N. Madnani, C. Monz, P. Resnik and M. Subotin, “The Hiero machinetranslation system: extensions, evaluation, and analysis,”, In Proc.Human Language Technology and Empirical Methods in Natural LanguageProcessing, pp. 779-786, 2005 (“Chiang05”); and (3) K. Yamada and K.Knight “A decoder for syntax-based statistical MT”. In Proc. Associationfor Computational Linguistics, 2002 (“Yamada02”). Alignment is performedword-to-word; translation examples, or phrase-pairs are matched at theword level; and word-based language models are applied. Hierarchicaltranslation modules such as those in Chiang05, and syntax-basedtranslation models such as in Yamada02, extend on this by introducingintermediate structure. However, these approaches still require exactword matches. As each word is treated as a separate entity, these modelsdo not generalize to unseen words.

One embodiment of class-based machine translation is class-basedstatistical machine translation, in which a foreign language sentence f₁^(J)=f₁, f₂, . . . , f_(J) is translated into another language e^(I)₁=e₁, e₂, . . . , e_(I) by searching for the hypothesis ^e^(I) ₁ withmaximum likelihood, given:^e ^(I) ₁=argmax P(e ^(I) ₁ |f ^(J) ₁)=argmax P(f ^(J) ₁ |e ^(I) ₁)=·P(e^(I) ₁)Classes can be semantic classes, such as named-entities, syntacticclasses or classes consisting of equivalent words or word phrases. As anexample we describe the case when named-entity classes are incorporatedinto the system.

The two most informative models applied during translation are thetarget language model P(e^(I) ₁) and the translation model P(f^(J)₁|e^(I) ₁). In a class-based statistical machine translation frameworkP(f^(J) ₁|e^(I) ₁) is a class-based translation model (FIG. 3, model23), and P(e^(I) ₁) is a class-based language model (FIG. 3, model 24).

Class-based models for a statistical machine translation framework canbe trained using the procedure shown in FIG. 10. First, the trainingcorpora of sentence pairs are normalized (step 100) and tagging models(FIG. 3, model 22) are used to tag the corpora (step 101). One approachto do this is described in Lafferty01. In this step, sentences thatcombine to form a training-pair can be tagged independently, taggedjointly, or tags from one language can be projected to the other. Afterthe entire training corpus is tagged, words within sentence-pairs arealigned (step 102). Alignment can be accomplished using currentapproaches such as those described by Franz Josef Och, ChristophTillmann, Hermann Ney: “Improved Alignment Models for StatisticalMachine Translation”; pp. 20-28; Proc. of the Joint Conf. of EmpiricalMethods in Natural Language Processing and Very Large Corpora;University of Maryland, College Park, Md., June 1999; and Brown, PeterF., Stephen A. Della Pietra, Vincent J. Della Pietra, and R. L. Mercer.1993. “The mathematics of statistical machine translation: Parameterestimation,” Computational Linguistics, vol 19(2):263-311. In this step,multi-word phrases within a tagged entity (i.e. “New York”) are treatedas a single token. Next, phrases are extracted (step 103) using methodssuch as Koelm07 to generate class-based translation models (FIG. 3,model 23). The tagged corpus is also used to train class-based targetlanguage models (FIG. 3, model 24). Training may be accomplished using aprocedure such as that described in B. Suhm and W. Waibel, “Towardsbetter language models for spontaneous speech’ in Proc. ICSLP-1994, 1994(“Suhm94”). (step 104).

To translate an input sentence the method illustrated in FIG. 11 isapplied. First, the input sentence is normalized (step 105) and tagged(step 106) using a similar procedure as that applied to the trainingcorpora. The input sentence is tagged using a monolingual tagger (FIG.3, model 22). Next, the input sentence is decoded using class-based MTmodels (FIG. 3, models 23 and 24). For class-based statistical machinetranslation decoding is performed using the same procedure used instandard statistical machine translation, However, phrase-pairs arematched at the class-level, rather than the word, as shown in theexample below.

Given the tagged input sentence:

the train to @PLACE.city {Wheeling} leaves at @TIME {4:30} the followingphrases can be matched:

train #

leaves #

@PLACE.city # @PLACE.city @TIME # @TIME at @TIME # @TIME 

the train to @PLACE.city # @PLACE.city 

leaves at @TIME #

 @TIME 

word or phrases within a class (i.e.: @PLACE.city {wheeling}, @Time{4:30}) are either passed directly through, which is the case fornumbers/times, or the translation is determined from the translationmodel. Users can add new words to the translation model via the “UserField Customization Module” (FIG. 1, module 12). If the user hadpreviously added the city name “Wheeling” (as detailed in the example inFIG. 6), then the translation model will also contain the followingphrase:

@PLACE.city # Wheeling #

Search is performed to find the translation hypothesis with maximumlikelihood P(f^(J) ₁|e^(I) ₁)·P(e^(I) ₁) given the translation modelprobability P(f^(J) ₁|e^(I) ₁) (FIG. 3, model 23) and the MT class-basedlanguage model probability P(e^(I) ₁) (FIG. 3, model 24).

Given the above input sentence and phrases the resulting translationwill be:

-   -   @PLACE.city {        □□□@TIME(4:30}

which is a correct translation of the input sentence.

In this example, even though the word “Wheeling” did not appear in thetraining corpora, after the user has entered the word via the “UserField Customization Module” (FIG. 1, module 12) the system is able tocorrectly translate the word. Furthermore, as the word-class is known(in this example “@PLACE.city”) the system is able to select bettertranslations for surrounding words and will order the words in thetranslation output correctly.

Parallel Tagging of Multilingual Corpora

In an embodiment, a labeled parallel corpora is obtained byindependently tagging each side of the training corpora with monolingualtaggers and then removing inconsistent labels from each sentence-pair.In this approach, for each sentence-pair (Sa,Sb) the label-sequence-pair(Ta,Tb) is selected which has maximum conditional probabilities P(Ta,Sa)and P(Tb,Sb). If the occurrence count of any class-tag differs betweenP(Ta,Sa) and P(Tb,Sb), that class-tag is removed from thelabel-sequence-pair (Ta,Tb). One method to estimate P(Ta,Sa) andP(Tb,Sb) is by applying conditional random field-based tagging modelsLafferty01. An example of a feature set used during monolingual taggingis shown in FIG. 11.

In an embodiment, labeling consistency across sentence-pairs can befurther improved by using the target word extracted from word-alignment(wb,j in FIG. 11), in addition to monolingual features.

In another embodiment, both sentences in the translation-pair arejointly labeled while applying the constraint that the class-tag setsmust be equivalent. Specifically, for the sentence-pair (Sa,Sb) wesearch for the label-sequence-pair (Ta,Tb) that maximizes the jointmaximum conditional probability

λa P(Ta,Sa) - λb P(Tb,Sb) where, Oi(Ta)= Oi(Tb) for 1 ≦ i ≦ M Oi(Ta)occurrence count of class-tag i in label sequence Ta (number ofentities, not word count) M total number of classes λa, λb scalingfactorsif the performance of the monolingual models differ significantly, Xaand Xb can be optimized to improve bilingual tagging performance.

In an embodiment, in the case where no manually annotated corpora isavailable for a specific language, labels can be generated by projectinglabels from a first language where labels are known, across thesentence-pairs in the training corpora to the non-annotated language.One approach to do this is described in D. Yarowsky, G Ngai and R.Wicentowski, “Inducting Multilingual Text Analysis Tools via RobustProjection across Aligned Corpora,” In Proc. HLT, pages 161-168, 2001(“Yarowsky01”). Example System and Evaluation of Class-based MachineTranslation

Through experimental evaluation, we show that class-based machinetranslation, as detailed above, improves translation performancecompared to previous approaches. Furthermore, we show that by using theparallel tagging approach described above, translation accuracy isfurther improved.

A system for translation between Japanese and English developed for thetourist domain was evaluated. A description of the training and testingdata is shown in Table 1.

TABLE 1 Training and Test Data English Japanese Parallel TrainingCorpora number of sentence-pairs 400k number of tokens 3,257k 3,171kaverage sentence length 8.7 8.5 Manually tagged training data (subset ofabove data) training (no. sentence-pairs) 12600 held-out Test (no.sentence-pairs) 1400 Test set number of sentence-pairs 600 number oftokens 4393 4669 average sentence length 7.3 7.8 OOV rate 0.3% 0.5%

To realize effective class-based SMT, accurate and consistent taggingacross sentence-pairs is vital. We investigated two approaches toimprove tagging quality; first, the introduction of bilingual featuresfrom word-alignment; and second, bilingual tagging, where both sides ofa sentences-pair are jointly tagged. From the parallel training corpora14,000 sentence-pairs were manually tagged using the 16 class labelsindicated in Table 2.

TABLE 2 Classes Used in Evaluation System Class Class labels Numbercardinal, ordinal, sequence, letter Time time, date, day, month Personfirst name, last name Place city, country, landmark Organizationairline, hotel, company name

From this manually labeled set, we selected 10% (1400 sentence-pairs)which contained one or more tags as held-out data to evaluate taggingaccuracy.

First, the performance of the baseline, monolingual CRF-based taggerswas evaluated. Each side of the held-out set was labeled independently,using language dependent models. The output was then compared to themanual reference. The tagging accuracy for various metrics are shown inTable 3.

TABLE 3 Monolingual and Bilingual Tagging Accuracy on Held-Out TrainingSet % correctly English Japanese Bilingual tagged sentence- TaggingScheme P R F P R F P R F pairs monolingual 0.95 0.89 0.92 0.94 0.88 0.910.88 0.80 0.84 80% +alignment features 0.97 0.85 0.91 0.98 0.93 0.950.95 0.82 0.88 82% +remove inconsistent tags 0.99 0.83 0.90 0.99 0.820.90 0.99 0.81 0.89 82% bilingual tagging 0.98 0.92 0.95 0.98 0.92 0.950.97 0.90 0.93 92% +alignment features 0.98 0.93 0.96 0.98 0.93 0.960.98 0.92 0.95 92%

For the bilingual tagging, a tag is considered correct if the entity iscorrectly labeled on both sides of the corpora. The right hand columnindicates the percentage of sentence-pairs in which both sides weretagged correctly. Although the F-score is above 0.90 for the independentlanguages, the bilingual tagging accuracy is significantly lower at0.84, and only 80% of the sentence-pairs were correctly tagged.Incorporating alignment features into the monolingual taggers improvedprecision for both languages and significantly improvement recall forthe Japanese side, however, the percentage of correctly taggedsentence-pairs increased only slightly. Removing inconsistent tagsacross sentence-pairs improved precision, but the number of correctlytagged sentence-pairs did not improve.

Next, the effectiveness of bilingual tagging was evaluated using theapproach described above. The tagging accuracy of this approach, andwhen word alignment features were incorporated are shown in the lower 2rows of Table 3. Compared to the monolingual case, bilingual taggingsignificantly improved tagging accuracy. Not only did taggingconsistency improve (the F-score for bilingual tagging increased from0.84 to 0.95), but the tagging accuracy on both the English andJapanese-sides also improved. Incorporating word-alignment featuresgained a further small improvement in tagging accuracy for all measures.

The effectiveness of the system was further evaluated by comparing theperformance of three class-based systems and a baseline system that didnot use class models.

For the baseline system phrase-based translation models were trainedusing the Moses toolkit such as described in Koehn05 and GIZA++(such asthat used by Franz Josef Och, Hermann Ney. “A Systematic Comparison ofVarious Statistical Alignment Models”, Computational Linguistics, volume29, number 1, pp. 19-51 March 2003). 3-gram language models were trainedusing the SRILM toolkit of A. Stolcke “SRILM—an extensible languagemodeling toolkit”, In Proc. of ICSLP, pp. 901-904, 2002. Decoding wasperformed using our PanDoRA decoder. The decoder is described in YingZhang, Stephan Vogel, “PanDoRA: A Large-scale Two-way StatisticalMachine Translation System for Hand-held Devices,” In the Proceedings ofMT Summit XI, Copenhagen, Denmark, Sep. 10-14, 2007. Systems werecreated for both translation directions J→E (Japanese to English) andE→J (English to Japanese) using the training set described in Table 1.The data used to train the target language models were limited to thiscorpora. The translation quality of the baseline system was evaluated ona test-set of 600 sentences. One reference was used during evaluation.The BLEU-score for the J→E and E→J systems were 0.4381 and 0.3947,respectively. BLEU-score is described in Kishore Papineni, Salim Roukos,Todd Ward and Wei-Jing Zhu “BLEU: a Method for Automatic Evaluation ofMachine Translation, “In Proc. Association for ComputationalLinguistics, pp. 311-318, 2002. Translation quality using threedifferent tagging schemes was evaluated:

+num: 8 classes related to numbers, times

+NE-class: above, +8 classes for named-entities

+Bi-Tagging: above 16 classes, training corpora tagged bilingually

Monolingual tagging was applied for the +num and +NE-class cases, andtags that were inconsistent across a sentence-pair were removed. In the+Bi-Tagging case, bilingual tagging incorporating word alignmentfeatures were used. For each tagging scheme, the entire training corporawas tagged with the appropriate set of class-labels. Class-basedtranslation and language models were then trained using an equivalentprocedure to that used in the baseline system. During testing the inputsentence was tagged using a monolingual tagger. All named-entities inthe test set were entered into the user dictionary to be used duringtranslation.

The performance on the 600 sentence test-set for the baseline andclass-based systems are shown in terms of BLEU-score for the J→E and E→Jsystems in Table 4.

TABLE 4 Translation Quality of Class-based SMT Translation Quality (BLEU[Papineni02]) System J→E E→J Baseline 0.4381 0.3947 +num 0.4441 0.4104+NE-class 0.5014 0.4464 +Bi-Tagging 0.5083 0.4542

The class-based SMT system using number and time tags (+num), obtainedimproved translation quality compared to the baseline system for bothtranslation directions. For these models, BLEU-scores of 0.4441 and0.4104 were obtained. When a class-based system using named-entityclasses in addition to number and time tags was applied, translationquality improved significantly. BLEU-scores of 0.5014 for the J→E systemand 0.4464 for the E→J case were obtained. When bilingual tagging wasused to tag the training corpora (+Bi-Tagging) a further 0.8 point gainin BLEU was obtained for both translation directions. On the 14% ofsentences in the test-set which contained one or more named-entities the(+Bi-Tagging) system outperformed the monolingually tagged system(“+NE-class”) by up to 3.5 BLEU points.

While the foregoing has been set forth in considerable detail, it is tobe understood that the drawings and detailed embodiments are presentedfor elucidation and not limitation. Design and configuration variationsmay be made but are within the principles of the invention. Thoseskilled in the art will realize that such changes or modifications ofthe invention or combinations of elements, variations, equivalents, orimprovements therein are still within the scope of the invention asdefined in the appended claims.

Speech Translation Favorites

Frequently, users may say the same phrase or sentence repeatedly in afield situation. To eliminate the need to re-speak the same phrases andsentences over and over again, embodiments of the invention provide aspeech translation favorites module, which stores frequently usedphrases for rapid play-back. This favorites modules differs from a plainlist or phrase book in one most important aspect: it gets filled andbuilt by the speech translation device, and thus, does not require abilingual speaker to be on hand to know the correct translation to aterm or phrase. The favorites module is programmed to enable a user toperform the following functions: Copy bilingual sentence-pair from thespeech translation interaction window to a favorites list; provideediting capability to the newly copied bilingual sentence-pair, so auser can modify both input and output string; and provide the ability toplay back the target language side of the added sentence pair byapplying the synthesis module. With the favorites list in place, a usercan simply play back various accumulated phrases from the favoriteslist, without, speaking them first, invoking them by clicking on theselected favorite or by way of a voice command or key phrase. This savestime in field situations. At the same time the favorites list providesthe full flexibility of a full two-way speech-to-speech translator sinceit does not require a linguistically trained expert knowledgeable ofboth languages to build such a list. A customized list can be built bythe user in the field and on the fly.

In addition to the basic speech translation system shown in FIG. 1 anembodiment of this system will add additional functionality to allowusers to playback predefined phrases via TTS (FIG. 1, modules 3 and 7).An example graphical user interface for this functionality is shown inFIG. 16. While using the speech translation system the users can selectany output generated by the system and add this to their favor list(step 34 b). The system will check if the sentence-pair already existsin the “Translation Favorites” list (step 109) and if not will append it(step 109 a). A possible graphical user interface for thisphrase-addition step is shown in FIG. 13. In this example the user canpress a graphical button (item 127) to add the current bilingualsentence-pair to the user's “Translation Favorites” list. Instead ofperforming speech translation, the user can enter the “TranslationsFavorites” mode (step 15 f). In this mode (detailed in FIG. 13) Thesystem allows users to select a sentence-pair for playback (steps 110,111), edit sentence-pairs currently in the list (steps 112,113), deletea sentence-pair from the list (steps 114, 115) or append a sentence-pairto the list (steps 116, 117) by typing in the required information.

Speech Translation Modes

Even when performing speech translation limited to one language pair,there are variations in language use, vocabularies and speaking styledepending on many factors, including (without limitation) socialsituation, dialect, relative relations between the speakers, socialrelationship between speakers, gender and age of speaker or listener,location or speaker and listener, activity, environment, regionalexpression and context that are typically not differentiated by astandardized speech translator. Yet, it is in many ways criticallyimportant to separate them to achieve socially appropriate results.Thus, the same user may speak formally in a formal context at work, inan informal colloquial manner at home with his/her family, and use slangat a party with friends. Similarly, there may be situationaldifferences, such as authoritative or submissive speaking, depending onwhether the device is used by a police/military officer on duty or as aclerk in a department store. In addition to language choices, weintroduce a language “mode”. This mode operates like a switch thatswitches the device into the appropriate speaking mode, andmodifies/conditions the modeling of several system subcomponentsaccordingly. Language modes then affect the operation of the system, byapplying language-mode dependent ASR, MT and TTS models, or by simplyfiltering the output of ASR and MT components. The choice of a mode isgiven to the user by a mode switch or setting (“polite”, “informal”,etc.) or by inferring the appropriate mode perceptually (for example,the gender or a speaker, his/her location, his/her level of formality,etc.).

The basic speech translation system shown in FIG. 1 performs speechrecognition (modules 2 and 9) using a single set of ASR models perlanguage, machine translation (modules 3 and 8) using a single set of MTmodels per language-pair, and speech generation (modules 3 and 7) usinga single set of TTS models per language. In one embodiment of thissystem, multiple language mode-dependent models will be available to thesystem rather than a single set of models. Specific models (ASR, MT and‘ITS) are developed for specific modes of communication includingformal/colloquial/slang/rude, authoritative/submissive, andstandard/dialectal language. Users either explicitly specify which modethey wish to use via the graphical user interface or the language modecan be estimated in the User Field Customization Module (item 12), basedon device location, input speech or discourse history. Differentlanguage modes will generate different translation and speech outputdepending on the communication-style they are tuned towards, and willconstrain the speech recognition components to the type of language usedin that communication-style. In another embodiment, different languagemodes will be realized by simply filtering the output of the speechrecognition (modules 2 and 9) and machine translation components(modules 3 and 8). For example while in formal mode, slang or rudephrases will be filtered from the ASR and MT output, be replaced with astar symbol (*) in the display of the graphical user interface, and bereplaced with an audible beep during TTS (modules 3 and 7). The UserField Customization Module (item 12) will contain the specific lists ofwords to be filtered for each language mode.

Speech Recognition Lexicon Selection Based on User Repair and Boosting

To run on small devices it is frequently not possible to carry a largedictionary of words that provides a reasonable good coverage for alanguage. The proposed method circumvents this problem by buildinginitial systems with considerably smaller dictionaries for efficiency.Coverage by contrast is then generally a problem as many common wordsmay not be available in the systems dictionaries. To recovergenerality/robustness without paying the price of more memoryrequirements, a method is disclosed that can achieve a tighter moretargeted dictionary and language model through personalization andcustomization of the system by the user. In this manner, the systemdesign sacrifices only some generality of vocabularies of an overalluser population, but retains the generality of vocabulary use by theindividual owner and user of the device. Prior research shows, forexample, that discussions between human conversant around a certaintopic of interest will generally only have vocabulary sizes of about4,000 words, while general speech translation systems may havevocabulary sizes of 40,000 words or more (in English). The system wouldtherefore be delivered in a state where vocabulary is more severelycurtailed than in larger more general systems and thus be moreparsimonious in memory use than a larger system. With vocabularies of4,000-10,000 words, search trees, language models and pronunciationdictionaries can be reduced dramatically over vocabulary sizes of 40,000or more. In this case, however, we will generally observe a largermismatch between the vocabulary of the system and the desired vocabularyof the user, and out-of-vocabulary words will appear in the spokenutterances. Now, the proposed system will come with a large backgrounddictionary, and large pre-trained language models. This is possiblewithout loss of advantage, since the large dictionaries and languagemodels can be stored in flash memories that are typically available inabundance (e.g. to store music, pictures, etc.) on modern mobile phones.When an out-of-vocabulary item occurs the system now provides an easymethod to correct the consequential misrecognition by various correctivemechanisms. Once the correction has been noted, the appropriatedictionaries and models (recognition, translation, synthesis) can beretrieved and added or replace less useful ones.

The speed of the speech translation system shown in FIG. 1 is dependenton the vocabulary size of the speech recognition models (item 17)applied. In an embodiment of the system recognition is performed with amedium sized recognition vocabularies consisting of around 40,000entries. This vocabulary size provides reasonable coverage over possiblewords uttered by users and allows speech recognition (step 27) to beperformed reasonably fast. In addition to this method, an additionalembodiment could be realized using a much smaller initial recognitionvocabulary (item 20) and language model (item 19) consisting of lessthan 10,000 vocabulary entries. When the user identifies a new wordusing the Correction and Repair Module (module 11) the appropriatespeech recognition models (item 17) will be updated via the User FieldCustomization Module (module 12). This procedure is shown in FIG. 3,steps 35, 36 and 37. Once identified the new word is incorporated intothe system as shown in FIG. 5.

Automatic Identification of the Input Language

In current speech translators a user has to select a record button thatpertains to the language of the speaker/user. In speech translators fortwo-way dialogs, this means that at least two record buttons have to beprovided for the two possible language inputs. This, unfortunately,wastes screen real estate and can lead to user errors when the wrongbutton is pushed. In the interest of simplification, we propose toeliminate this source of user confusion, but providing automaticlanguage identification first and then produce translation in the otherlanguage, no matter which language was spoken.

The basic speech translation system shown in FIG. 1 operates over twolanguages, language L_(a) and language L_(b). For consecutivetranslation the user holds down a push-to-talk button (FIG. 3, step 15b) to start the speech recognition process (FIG. 3, step 27). Theidentity of the button pushed will determine if recognition is performedin language L_(a) (using FIG. 1, module 2) the primary users language,or in language L_(b) (using FIG. 1, module 9) the language of the dialogparticipant. In addition to this approach, an embodiment of the systemwill perform automatic identification of the input language (step 27 a)to select the appropriate ASR module to use for recognition (step 27 b).In another embodiment, language identification (step 27 a) is used toselect the appropriate ASR module where modules exist for more than twolanguages. In another embodiment, it is also applied during simultaneoustranslation.

Language Learning from Speech Translation

Speech translators today are aiming to provide two-way speech dialogcommunication for people who don't speak each other's languages.Frequently, though, a user may wish to learn another person's languagethemselves as well. To provide such possibilities, we expand the speechtranslator function by the function of providing language instruction tothe human user. Such an expanded speech translator/languagetutor/trainer differs from other language instruction/tutoring softwareproducts in two fundamental ways: 1.) the disclosed combined languagesystem provides a speech translator for language support when the user'slanguage abilities are inadequate to navigate a real situation in actualuse, and 2.) the combined system can then provide much more customized,targeted language learning drills and instruction that is respondingspecifically to a user's language learning interest, situations, and itbases its instruction on what it can observe from a user's languageusage during speech translation dialog use. Thus, a user may conversewith other individuals through use of the speech translator over aperiod of time, and then gradually attempt to learn for him/herself thekey concepts, vocabularies, language constructs that he/she often usesand wishes to learn for him/herself. Thus a language learning drill canbe personalized and targeted much more concretely at the specificlanguage needs of an individual user than static impersonal languagelearning books or software would and thus it presents a much morepersonal and alive human language learning experience. In the preferredembodiment, the language learning subsystem builds vocabulary, syntax orconversational drills that derive from the sentences found in the recenthistory of the speech translator.

In addition to the basic speech translation system shown in FIG. 1 anembodiment of this system will add additional functionality to allowusers to learn language Lb as they use the system in the field. Thelanguage learning module (item 12 a) observes sentences a user hasuttered over a period of time (items 14 e, 14 f) and builds a profile ofcommon language usage statistics. Statistics include typical syntacticconstructs and vocabulary usage. When the user enters the languagelearning mode (step 15 g), the system will consolidate statistics fromrecent system logs (step 118) and use this information to constructvocabulary drills based on word usage by the user and related wordsbased on topic or usage as determined by word frequency or semantic wordclustering (step 119). A similar approach will be used to generatesyntax drills (step 120). The drills will be presented to the user (step121), and if performance is not satisfactory (step 122) the user willperform the drill again. In parallel to the automatic construction oflanguage learning drills, the user is also provided with direct controlover his/her language learning drills. Each sentence spoken in thespeech translator can also be directly copied to the learning module(step 34 c), so that its words and expressions appear in the subsequentlearning drills. When sentences are added to the active learning drill,the system first checks if the drill contains the sentence (step 118 a)and if it does not before appends it (step 118 b).

Speech Translation of Telephone Conversation

In the previous disclosures, we have considered speech translators forportable devices such as smart phones and PDA's. In all thesedeployments, the speech translator acts as an interpreter between twopeople in a face to face dialog situation where the device acts as thetranslator. We expand this notion, by using a speech translator on atelephone as an interpreter between people speaking over that telephoneas a transmission channel with each other. To achieve thisfunctionality, we modify the user interface. Speech is now arriving viathe microphone of the user of the telephone as well as by the signaltransmitted over the telephone line and is recognized and translated.The speech translation is performed in either consecutive translationmode (a speaker speaks, and then waits for translation, before the otherspeaker takes his turn) as well as simultaneous translation mode (wheneither speaker can speak continuously while the translator performsspeech translation output in parallel).

The basic speech translation mode operates using speech input frommicrophones (items 1 and 10) and loudspeakers (items 5 and 6) located onthe device. In addition to this mode, speech translation can also beperformed over a telephony network. In this case audio for language Lbis transmitted over the telephone network and the microphone (item 10)and loudspeaker (item 5) for language Lb will be physically located on arecipient's telephony handset. When operated over a telephony networkspeech recognition (modules 2, 9) and machine translation (modules 3, 8)can be carried out in two different manners. In consecutive translationthe user holds a push-to-talk button down (step 15 b) to startrecognizing an utterance (step 27). The utterance is then recognized andtranslated using the steps shown in FIG. 3. In simultaneous translation(steps 15 d, 34 a) no button push is required but the systemcontinuously recognizes and translates all speech present on bothmicrophone inputs (items 1 and 10). Speech translation output from (step33) is then provided either acoustically, overlaying or in place of theoriginal speaker's speech, or visually, by displaying text on a user'stelephone device.

Information Extraction Based on Recognized and Translated Speech

Speech Recognizers and Translators operating on a smart phone can alsoprovide information as to a user's speech content. We propose to expandthe speech recognizer and translator to extract topical information fromtwo conversants’ speech. Such information is then used to seek relevantrelated information on the internet. Such information is then presentedto the user. There are multiple uses of such conversation enabledinformation extraction. It could be used to provide more targetedadvertising (perhaps in return for cheaper calling rates). It could alsobe used to provide the user with helpful supporting information (forexample, calling up flight schedules, hotel availabilities & rates,recalling a person's contact details, etc.) when a conversation mentionscertain topics, people, places, or activities. This information can alsobe recalled bilingually from sources in either of the languages handledby the speech translator.

The information extraction module (module 12 a) extracts key words andphrases from system logs (items 14 e and 14 f) generated by the speechrecognition (modules 3, 8) and machine translation (modules 3, 8)components. First, usage statistics from recent system logs (step 123)are generated. Next, relevant information is obtained from the internetor local knowledgebase (item 125) based on keyword occurrence andlanguage usage (step 124). This information is subsequently presented tothe user (step 126) via the screen of the device (FIG. 1, item 13).Presented information will include targeted advertising and supportiveinformation. Supportive information includes flight schedules, hotelavailability and rates, and contact details of persons. Information canbe presented bilingually in either language (L_(a) or L_(b)) bysearching based on keywords in the output of machine translation(modules 3, 8).

While the foregoing has been set forth in considerable detail, it is tobe understood that the drawings and detailed embodiments are presentedfor elucidation and not limitation. Design variations may be made butare within the principles of the invention. Those skilled in the artwill realize that such changes or modifications of the invention orcombinations of elements, variations, equivalents, or improvementstherein are still within the scope of the invention as defined in theappended claims. Also, the examples and experimental results illustratedherein are exemplary and are not intended to limit the scope of theembodiments of the invention.

What is claimed is:
 1. A method comprising: receiving from a user anutterance in a first language including a first term; by a speechtranslation system, translating the utterance from the first languageinto a second language; receiving an indication from the user toinitiate a user customization process for customizing one or moremodules of the speech translation system to the user; and under the usercustomization process: receiving an indication from the user to add thefirst term to one or more modules of the speech translation system; inresponse to the received indication from the user, determining wordclass information for the first term; adding, by the speech translationsystem, the first term, the determined word class information, and atleast a portion of the translation of the utterance in the secondlanguage to a first machine translation module associated with the firstlanguage of the speech translation system; and adding the first term andthe at least a portion of the translation of the utterance in the secondlanguage to a shared database for a community such that thecustomization performed by the user is available for use by other usersof the community in translations by the speech translation system. 2.The method of claim 1, further comprising: retrieving a second term fromthe shared database; and adding the second term from the shared databaseto the first machine translation module.
 3. The method of claim 1,wherein the at least a portion of the translation of the utterance inthe second language added to the shared database comprises an incorrector incomplete translation, and further comprising: requesting, with thefirst term added to the shared database, a translation correction forthe first term.
 4. The method of claim 1, further comprising: retrievinga corrected translation of the first term from the shared database; andadding the corrected translation from the shared database to the firstmachine translation module.
 5. The method of claim 4, wherein thecorrected translation of the first term in the shared database isprovided by a second user of the community.
 6. The method of claim 5,wherein the shared database stores terms associated with one or morefields comprising one or more of: names, expressions, special terms. 7.The method of claim 1, further comprising: displaying simultaneously intext, on a user interface display of the speech translation system, atleast (i) the received utterance in the first language, and (ii) thetranslation of the utterance in the second language.
 8. The method ofclaim 1, wherein translating the utterance in the first language intothe second language comprises generating a translation in the secondlanguage via either a rule-based model or a statistical model.
 9. Themethod of claim 1, further comprising: in response to the receivedindication from the user, determining a pronunciation in the firstlanguage for the first term; and adding the first term, the determinedword class information, and the pronunciation in the first language to afirst recognition lexicon of the first language of a first automaticspeech recognition module of the speech translation system.
 10. Themethod of claim 1, further comprising: saving the utterance and thetranslation as sentence pairs upon instruction by the user to save thesentence pairs as a favorite in a speech translation favorites moduleconfigured to store a list or hierarchical inventory of such sentencepairs wherein each favorite can be customized and played directly uponuser selection in either the first or second language.
 11. The method ofclaim 1, further comprising: in response to the received indication fromthe user, determining a pronunciation in the first language for thefirst term; and adding the pronunciation in the first language to theshared database.
 12. The method of claim 1, further comprising: inresponse to the received indication from the user, determining apronunciation in the second language for the first term; and adding thepronunciation in the second language to the shared database.
 13. Acomputer program product comprising a non-transitory computer-readablestorage medium containing computer program code for performing thesteps: receiving from a user an utterance in a first language includinga first term; translating, by a speech translation system, the utterancein the first language into a second language; receiving an indicationfrom the user to initiate a user customization process for customizingone or more modules of the speech translation system to the user; andunder the user customization process: receiving an indication from theuser to add the first term to one or more modules of the speechtranslation system; in response to the received indication from theuser, determining word class information for the first term; adding bythe speech translation system the first term, the determined word classinformation, and at least a portion of the translation of the utterancein the second language to a first machine translation module associatedwith the first language of the speech translation system; and adding thefirst term and the at least a portion of the translation of theutterance in the second language to a shared database for a communitysuch that the customization performed by the user is available for useby other users of the community in translations by the speechtranslation system.
 14. The computer program product of claim 13,further comprising computer program code for performing the steps:retrieving a second term from the shared database; and adding the secondterm from the shared database to the first machine translation module.15. The computer program product of claim 13, wherein the translation inthe second language added to the shared database comprises a poortranslation, further comprising computer program code for performing thestep: requesting, with the first term added to the shared database, atranslation correction for the first term.
 16. The computer programproduct of claim 13, further comprising computer program code forperforming the steps: retrieving a corrected translation of the firstterm from the shared database; and adding the corrected translation fromthe shared database to the first machine translation module as.
 17. Thecomputer program product of claim 13, wherein the corrected translationof the first term in the shared database is provided by a second user ofthe community.
 18. The computer program product of claim 17, wherein theshared database stores terms associated with one or more fieldscomprising one or more of: names, expressions, special terms.
 19. Thecomputer program product of claim 13, further comprising computerprogram code for performing the step: displaying simultaneously in text,on a user interface display of the speech translation system, at least(i) the received utterance in the first language, and (ii) thetranslation of the utterance in the second language.
 20. The computerprogram product of claim 13, wherein translating the utterance in thefirst language into the second language comprises generating atranslation in the second language via either a rule-based model or astatistical model.
 21. The computer program product of claim 13, furthercomprising computer program code for performing the steps: in responseto the received indication from the user, determining a pronunciation inthe first language for the first term; and adding the first term, thedetermined word class information, and the pronunciation in the firstlanguage to a first recognition lexicon of the first language of a firstautomatic speech recognition module of the speech translation system.22. A system comprising: a computer processor; and a memory, comprising:an automatic speech recognition module for receiving from a user, anutterance in a first language including a first term associated with afield term; a translation module for translating the utterance from thefirst language into a second language; a user field customization modulefor receiving an indication from the user to initiate a usercustomization process for customizing one or more modules of the speechtranslation system to the user; and under the user customizationprocess: for receiving an indication from the user to add the first termto one or more modules of the speech translation system, for, inresponse to the received indication from the user, determining wordclass information the first term, for adding by the speech translationsystem the first term, the determined word class information, and atleast a portion of the translation of the utterance in the secondlanguage to a first machine translation module associated with the firstlanguage of the speech translation system; and for adding the first termand the at least a portion of the translation of the utterance in thesecond language to a shared database for a community such that thecustomization performed by the user is available for use by other usersof the community in translations by the speech translation system.